Antenna equipment

Abstract

To provide a technology that can suppress interference between multiple channels and achieve stable communication in an antenna device that uses an antenna to communicate between circuit boards.SOLUTION: An antenna device includes a first circuit board, a second circuit board arranged to face the first circuit board, a plurality of transmitting antennas provided on a main surface of the first circuit board, and a plurality of receiving antennas provided on a main surface of the second circuit board. The plurality of transmitting antennas and the plurality of receiving antennas are arranged such that a combination of a transmitting antenna and a corresponding receiving antenna faces each other between the first circuit board and the second circuit board. The distance between the transmitting antenna and the corresponding receiving antenna is smaller than the distance between the transmitting antenna and any of the transmitting antennas adjacent thereto.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to an antenna device.

Background Art

[0002] Patent Document 1 discloses an antenna device configured to communicate between circuit boards using an antenna.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to transmit a plurality of signals simultaneously between circuit boards, it is conceivable to form a plurality of transmitting antennas on one circuit board, form a plurality of receiving antennas on the other circuit board, and allocate a channel for each combination of the corresponding transmitting antenna and receiving antenna. In such a case, a technology capable of suppressing interference between a plurality of channels and realizing stable communication is required. This specification provides a technology capable of suppressing interference between a plurality of channels and realizing stable communication in an antenna device that communicates between circuit boards using an antenna.

Means for Solving the Problems

[0005] One embodiment of an antenna device disclosed herein may include a first circuit board, a second circuit board disposed opposite to the first circuit board, a plurality of transmitting antennas provided on the main surface of the first circuit board that faces the second circuit board, and a plurality of receiving antennas provided on the main surface of the second circuit board that faces the first circuit board. The plurality of transmitting antennas and the plurality of receiving antennas may be arranged such that the combination of the transmitting antenna and its corresponding receiving antenna faces the first circuit board and the second circuit board. The distance between the transmitting antenna and its corresponding receiving antenna may be smaller than the distance between the transmitting antenna and any adjacent transmitting antenna.

[0006] With the above antenna device, the distance between the transmitting antenna and the corresponding receiving antenna is relatively short, so the amount of radio wave propagation from the transmitting antenna to the receiving antennas other than the corresponding receiving antenna is relatively reduced. As a result, the directivity between the transmitting antenna and the corresponding receiving antenna is relatively increased. With the above antenna device, interference between multiple channels is suppressed and stable communication can be achieved. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-sectional view of one embodiment of an antenna device, schematically showing the cross-sectional view corresponding to line II in Figure 2. [Figure 2] Figure 1 is a plan view of the first circuit board of the antenna device, wherein the main surface of the first circuit board on which the transmitting antenna is installed is considered the plane. [Figure 3] This is a plan view of a first circuit board included in a modified example of the antenna device shown in Figure 1, wherein the plan view is defined as the main surface of the first circuit board on which the transmitting antenna is installed. [Figure 4]This is a plan view of a first circuit board included in a modified example of the antenna device shown in Figure 1, wherein the plan view is defined as the main surface of the first circuit board on which the transmitting antenna is installed. [Figure 5] (A) This is a circuit diagram showing an example of a circuit element connected between the first GND plates in Figure 4. (B) This is a circuit diagram showing another example of a circuit element connected between the first GND plates in Figure 4. [Modes for carrying out the invention]

[0008] As shown in Figure 1, the antenna device 1 comprises a first circuit board 10 and a second circuit board 20. The first circuit board 10 and the second circuit board 20 are housed in a housing (not shown). Such an antenna device 1 is not particularly limited, but may be used, for example, for communication between boards via a resin partition.

[0009] Each of the first circuit board 10 and the second circuit board 20 has a flat plate shape and can be made of a substrate of any material. Each of the first circuit board 10 and the second circuit board 20 is not particularly limited, but may be a circuit board made of a composite material of glass fiber and epoxy resin (i.e., FR-4). The thickness of each of the first circuit board 10 and the second circuit board 20 can be set to any thickness. The first circuit board 10 and the second circuit board 20 are arranged in parallel and facing each other. The first circuit board 10 and the second circuit board 20 may be arranged facing each other with a gap of, for example, several millimeters to several tens of millimeters between them. The space between the first circuit board 10 and the second circuit board 20 may be an air layer, or it may be a resin that seals the first circuit board 10 and the second circuit board 20. The resin may be, for example, epoxy resin. Each of the first circuit board 10 and the second circuit board 20 is equipped with various electronic circuits (not shown), and the electronic circuits mounted on the first circuit board 10 and the electronic circuits mounted on the second circuit board 20 are configured to operate at different operating voltages. Therefore, an antenna device 1 is provided to enable secure communication between the electronic circuits of the first circuit board 10 and the electronic circuits of the second circuit board 20.

[0010] As shown in Figures 1 and 2, a plurality of transmitting antennas 12 are provided on the main surface of the first circuit board 10 that faces the second circuit board 20. In this example, four transmitting antennas 12 are provided, but fewer or more transmitting antennas 12 may be provided. Each of the plurality of transmitting antennas 12 is formed by depositing a metal film on the main surface of the first circuit board 10, for example, using printing or etching technology. Each of the plurality of transmitting antennas 12 is not particularly limited, but may be formed by depositing a film of copper or aluminum, for example. Each of the plurality of transmitting antennas 12 extends from a feed point 12a to which a feed unit 14 is connected to an open end 12b and is composed of a monopole type antenna having a meander pattern. The feed unit 14 of each of the plurality of transmitting antennas 12 is connected to a corresponding transmitting circuit (not shown). Note that each of the plurality of transmitting antennas 12 may be composed of a dipole type antenna instead of a monopole type antenna. Furthermore, each of the multiple transmitting antennas 12 may be a chip antenna mounted on the main surface of the first circuit board 10 instead of such a pattern antenna. The multiple transmitting antennas 12 may each be antennas with a common structure, or they may each have some different structures. Typical types of antennas include, but are not limited to, meander type, loop type, spiral type, helical type, patch type, inverted F type, and plate-type inverted F type.

[0011] A first GND plate 16 is provided on the main surface of the first circuit board 10 on which the plurality of transmitting antennas 12 are provided. The first GND plate 16 is formed by depositing a metal film on the main surface of the first circuit board 10, for example, using printing or etching technology. The first GND plate 16 is not particularly limited, but may be formed by depositing a film of copper or aluminum, for example. The first GND plate 16 is provided so as to surround each of the plurality of transmitting antennas 12. The first GND plate 16 can function as a GND to exert a mirror image effect at each of the plurality of transmitting antennas 12.

[0012] Multiple receiving antennas 22 are provided on the main surface of the second circuit board 20 that faces the first circuit board 10. Each of the multiple receiving antennas 22 may be an antenna with the same structure as the transmitting antenna 12 provided on the first circuit board 10. That is, each of the receiving antennas 22 may be, for example, a monopole type antenna having a meander pattern. Each of the receiving antennas 22 may be an antenna with a different structure than the transmitting antenna 12. The feeding section of each of the multiple receiving antennas 22 is connected to the corresponding receiving circuit (not shown). Similar to the first circuit board 10, a second GND plate 26 is provided on the main surface of the second circuit board 20 on which the multiple receiving antennas 22 are provided. The second GND plate 26 is also provided so as to surround each of the multiple receiving antennas 22.

[0013] Multiple transmitting antennas 12 and multiple receiving antennas 22 are arranged so that the combinations of transmitting antennas 12 and their corresponding receiving antennas 22 face each other between the first circuit board 10 and the second circuit board 20. The antenna device 1 can communicate independently between the corresponding combinations of transmitting antennas 12 and receiving antennas 22. Thus, in the antenna device 1, a channel is assigned to each corresponding combination of transmitting antennas 12 and receiving antennas 22, and in this example, communication can be performed between the electronic circuits of the first circuit board 10 and the electronic circuits of the second circuit board 20 via four channels ch1 to ch4.

[0014] The transmitting antenna 12 on the first circuit board 10 and the receiving antenna 22 on the second circuit board 20 are configured to communicate using radio waves with frequencies on the order of GHz. As described above, the distance between the first circuit board 10 and the second circuit board 20, that is, the distance d1 between the transmitting antenna 12 and the receiving antenna 22, is, for example, a few millimeters to a few tens of millimeters. Specifically, the distance d1 between the transmitting antenna 12 and the receiving antenna 22 is 1 / 4 or less of the wavelength (λ) of the communication radio waves radiated from the transmitting antenna 12, and more preferably λ / (2π) or less.

[0015] When the distance d1 between the transmitting antenna 12 and the receiving antenna 22 is set to such a short distance, the region between the transmitting antenna 12 and the receiving antenna 22 becomes a region of roughly near-field, where a quasi-electrostatic field is dominant. The transmitting antenna 12, being a monopole type, is a radiation source that emits an electric field. Therefore, the transmitting antenna 12 and the receiving antenna 22 can communicate by utilizing the electric field radiated from the transmitting antenna 12.

[0016] As shown in Figure 2, the transmitting antenna 12 corresponding to channel ch1 is at a distance d2 from the transmitting antenna 12 corresponding to channel ch2, at a distance d3 from the transmitting antenna 12 corresponding to channel ch3, and at a distance d4 from the transmitting antenna 12 corresponding to channel ch4. Here, when the area where the first GND plate 16 is removed is defined as the formation range of the transmitting antennas 12, the distance between adjacent transmitting antennas 12 can be defined as the shortest distance between the formation ranges of adjacent transmitting antennas 12. Alternatively, the distance between adjacent transmitting antennas 12 may be the distance between the geometric centers of the transmitting antennas 12, or the distance between the feed points of the transmitting antennas 12.

[0017] In antenna device 1, the distance d1 between the transmitting antenna 12 and its corresponding receiving antenna 22 is smaller than the distances d2, d3, and d4 between the transmitting antenna 12 and any adjacent transmitting antennas 12. While not particularly limited, in this example d1 is approximately 10 mm, d2 is approximately 35 mm, d3 is approximately 30 mm, and d4 is approximately 47 mm. With such antenna device 1, because the distance between the transmitting antenna 12 and its corresponding receiving antenna 22 is relatively short, the amount of radio wave propagation from the transmitting antenna 12 to receiving antennas 22 other than its corresponding receiving antenna 22, i.e., non-corresponding receiving antennas 22 adjacent to the corresponding receiving antenna 22, is relatively reduced. As a result, the directivity between the transmitting antenna 12 and its corresponding receiving antenna 22 is relatively increased. Antenna device 1 suppresses interference between multiple channels ch1 to ch4 and enables stable communication.

[0018] Note that the distances d2, d3, and d4 may be 10 times or less the distance d1. In other words, the distances d2, d3, and d4 may be 2.5 times or less the wavelength (λ) of the radio wave for communication radiated from the transmission antenna 12. When the distances d2, d3, and d4 increase, it becomes a completely far-field region, and the generation of standing waves is a concern. Therefore, by setting the distances d2, d3, and d4 as described above, interference between the plurality of channels ch1 to ch4 can be suppressed, and stable communication can be performed.

[0019] As shown in FIG. 3, the first GND plate 16 may be divided by a slit 18 formed between adjacent transmission antennas 12. In this way, the first GND plate 16 is composed of a plurality of first GND plates 16 divided into island shapes, and each of the plurality of divided first GND plates 16 is formed around the corresponding transmission antenna 12. The width W18 of the slit 18 measured in the direction between adjacent first GND plates 16 is not particularly limited, but may be, for example, several millimeters. In this example, the width W18 of the slit 18 is about 4 mm. Note that the second GND plate 26 of the second circuit board 20 may also be similarly divided by a slit formed between adjacent reception antennas 22, and each of the plurality of divided second GND plates 26 may be formed around the corresponding reception antenna 22.

[0020] A part of the radio waves radiated from the transmission antenna 12 propagates horizontally while being repeatedly reflected by the GND plates 16 and 26 between the first circuit board 10 and the second circuit board 20. Since the first circuit board 10 is provided with a slit 18 (the same applies to the slit of the second circuit board 20), a part of the radio waves that have propagated horizontally leaks through the slit. Therefore, if a slit is formed in a part between adjacent GND plates 16 and 26, the amount of radio wave propagation from the transmission antenna 12 to the non-corresponding reception antenna 22 further decreases, so that the directivity between the transmission antenna 12 and the corresponding reception antenna 22 can be further enhanced. Note that a slit may not be formed in a part between adjacent GND plates 16 and 26. That is, a part between adjacent GND plates 16 and 26 may be connected. Also in this case, since at least a part of between adjacent GND plates 16 and 26 is provided with a slit, a part of the radio waves that have propagated horizontally can leak through the slit.

[0021] The area of each of the plurality of divided first GND plates 16 is (λ / 4) 2 or less, and more preferably (λ / (2π)) 2 or less. When the area of each of the plurality of divided first GND plates 16 becomes large, radio waves in the far field are likely to be generated, and standing waves must be considered. When the area of each of the plurality of divided first GND plates 16 is within the above range, the generation of radio waves in the far field is suppressed. Note that the shape of each of the plurality of divided first GND plates 16 is not particularly limited, and may be circular, polygonal, or irregular.

[0022] As shown in Figure 4, a circuit element 30 may be provided to connect the first GND plate 16 corresponding to channel 1 and the first GND plate 16 corresponding to channel 2. Such a circuit element 30 may be an inductor as shown in Figure 5(A), or an LC low-pass filter as shown in Figure 5(B). This type of circuit element 30 electrically isolates the first GND plates 16 in the high-frequency band corresponding to the communication radio waves radiated from the transmitting antenna 12. On the other hand, this type of circuit element 30 electrically connects the first GND plates 16 in the low-frequency band in which the transmitting circuit to which the transmitting antenna 12 is connected operates. As a result, the effective area of ​​the first GND plate 16 as seen from the transmitting circuit to which the transmitting antenna 12 is connected becomes larger. This improves the noise immunity of the antenna device 1. Note that this type of circuit element 30 may be provided not only between the first GND plate 16 corresponding to channel 1 and the first GND plate 16 corresponding to channel 2, but also between each of the divided multiple transmitting antennas 12. Furthermore, this type of circuit element 30 may also be provided between the divided second GND plates 26 of the second circuit board 20.

[0023] The features of the technology disclosed herein are summarized below. Note that the technical elements described below are independent elements that exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0024] (Feature 1) First circuit board and A second circuit board is positioned opposite the first circuit board, A plurality of transmitting antennas are provided on the main surface of the first circuit board that faces the second circuit board, The second circuit board comprises a plurality of receiving antennas provided on the main surface of the second circuit board that faces the first circuit board, The plurality of transmitting antennas and the plurality of receiving antennas are arranged such that the combination of the transmitting antenna and the corresponding receiving antenna faces each other between the first circuit board and the second circuit board. An antenna device in which the distance between the transmitting antenna and the corresponding receiving antenna is smaller than the distance between the transmitting antenna and any adjacent transmitting antenna.

[0025] (Feature 2) The antenna device according to feature 1, further comprising: a first GND plate provided on the main surface of the first circuit board on which the plurality of transmitting antennas are provided, and arranged to surround each of the plurality of transmitting antennas.

[0026] (Feature 3) The antenna device according to feature 2, wherein the first GND plate has slits formed in at least a portion of the area between adjacent transmitting antennas.

[0027] (Feature 4) The antenna device according to feature 3, wherein the first GND plate is divided by the slit.

[0028] (Feature 5) It further comprises a circuit element connecting the divided first GND plates, The antenna device according to feature 4, wherein the circuit element is an inductor or a low-pass filter.

[0029] (Feature 6) The antenna device according to any one of features 1 to 4, further comprising: a second GND plate provided on the main surface of the second circuit board on which the plurality of receiving antennas are provided, and arranged to surround each of the plurality of receiving antennas.

[0030] (Feature 7) The antenna device according to feature 6, wherein the second GND plate has slits formed in at least a portion of the area between adjacent receiving antennas.

[0031] (Feature 8) The antenna device according to feature 7, wherein the second GND plate is divided by the slit.

[0032] (Feature 9) It further comprises a circuit element connecting the divided second GND plates, The antenna device according to feature 8, wherein the circuit element is an inductor or a low-pass filter.

[0033] (Feature 10) The antenna device according to any one of features 1 to 9, wherein the distance between the transmitting antenna and the corresponding receiving antenna is 1 / 4 or less of the wavelength of the radio waves radiated from the transmitting antenna.

[0034] (Feature 11) The antenna device according to feature 10, wherein the transmitting antenna is a monopole or dipole type antenna.

[0035] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0036] 1: Antenna device, 10: First circuit board, 12: Transmitting antenna, 16: First GND board, 20: Second circuit board, 22: Receiving antenna, 26: Second GND board

Claims

1. First circuit board and A second circuit board is positioned opposite the first circuit board, A plurality of transmitting antennas are provided on the main surface of the first circuit board that faces the second circuit board, A plurality of receiving antennas are provided on the main surface of the second circuit board that faces the first circuit board, The first circuit board comprises a first GND plate, which is provided on the main surface of the first circuit board on which the plurality of transmitting antennas are provided, and which is arranged to surround each of the plurality of transmitting antennas, The plurality of transmitting antennas and the plurality of receiving antennas are arranged such that the combination of the transmitting antenna and the corresponding receiving antenna faces each other between the first circuit board and the second circuit board. The distance between the transmitting antenna and the corresponding receiving antenna is smaller than the distance between the transmitting antenna and any adjacent transmitting antenna. An antenna device in which a slit is formed in the first GND plate in at least a portion of the area between adjacent transmitting antennas.

2. The antenna device according to claim 1, wherein the first GND plate is divided by the slit.

3. It further comprises circuit elements connecting the divided first GND plates, The antenna device according to claim 2, wherein the circuit element is an inductor or a low-pass filter.

4. The antenna device according to claim 1, further comprising: a second GND plate provided on the main surface of the second circuit board on which the plurality of receiving antennas are provided, and arranged to surround each of the plurality of receiving antennas.

5. The antenna device according to claim 4, wherein the second GND plate has slits formed in at least a portion of the area between adjacent receiving antennas.

6. The antenna device according to claim 5, wherein the second GND plate is divided by the slit.

7. It further comprises a circuit element connecting the divided second GND plate, The antenna device according to claim 6, wherein the circuit element is an inductor or a low-pass filter.

8. The antenna device according to claim 1, wherein the distance between the transmitting antenna and the corresponding receiving antenna is 1 / 4 or less of the wavelength of the radio waves radiated from the transmitting antenna.

9. The antenna device according to claim 8, wherein the transmitting antenna is a monopole or dipole antenna.

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